Attachment for calipers.



R. A. JOHNSON.

ATTACHMENT FOR CALTPEHS. APPLTCATTON FILED'AUG.16,1915- 1 3QL34$ u Patented July 24, 1917.

WITNESSES: IN VENTOR Rate/"2 binary/z,

ATTORNEY.

ROBERT A. JOHNSON, OF SPRINGFIELD, MASSACHUSETTS.

ATTACHMENT FOR CALIPERS.

31 ,23 h3 ll2.

Specification of Letters latent.

Patented July 2st, i917.

Application filed August 16, 1915. Serial No. 45,622.

To all Mil/0722 it may concern Be it known that I, Bonner A. JorINsoN, a citizen of the United States of America, and resident of Springfield, in the county of Hampden and State of lllassachusctts, have invented certain new and useful 1mprovements in Attachments for Calipers, of which the following is a full, clear, and exact description.

This invention relates to an improvement in a. calipers, more especially a micrometer calipers of the form comprising an approximately semiircular yoke, the outer jaw of which is formed with a convex anvil member, while through the other portion of the yoke and the barrel extension thereof the movable and measuring or gaging jaw of the device is comprised,the invention more particularly relating to a simple form of removable appliance or attachment to be made use of for the measuring of an article or piece, one surface of which is concave and which could. not be measured or gaged with exactness between flat ends of the anvil jaw and the measuring jaw.

The improved device is fully described in conjunction with the accompanying draw-- ings and is set forth in the claim.

In the drawings 1- Figure 1 shows a side view of a micrometer calipers of well known and extensively used kind having the improved detachable appliance in place on the anvil provided jaw thereof.

Fig. 9. is a sectional view through the anvil comprising jaw with the device in its place thereon.

Fig. 3 is a perspective view of the device.

Figs. 4 and 5 are views to indicate by comparison between Figs. 5 and at the practical advantage derived in the use of the device.

In the drawings, A represents the yoke of the calipers having the barrel extension B,- 0 representing the anvil member or jaw, and 7) representing the movable shaft or measuring or gaging jaw.

The outer extremity d of the yoke,of which the anvil member a is formed as a cylindrical inward extension or boss,has a rounded or hemi-cylindrical edge,such being the usual contour or design of this part as usually made.

The detachable appliance D consists of a partially cylindrical clip or sleeve f to constrictively embrace the outer face or rounded edge and the opposite sides of the jaw (Z, the same having at its inner end, that its end, which when the clip is assembled on the calipers lies toward the jaw (Z, a wall 9 to overlie the end of the anvil member a, such wall being extended to convergence substantially to a point in the axis of the device.

As represented, the convergent portion 9 of such wall is of the form of a hemisphere.

The said wall has a short, curved flange 72/, opposite from and continued with the round ed back of the partially cylindrical clip or sleeve for en agement with the end of the anvil member a, as particularly represented in Fig. 2.

The split sleeve-like portion or clip 7 of the appliance is provided with outwardly turned lip portions j j at its opposite sides sitlbstantially as represented, for facilitating the engagement of the device on the portion d of the caliper frame.

When the appliance is to be used, it is positioned 011 the aw (Z with the inner face of the wall 9 against the anvil member and with the back of the clip closely against and with constrictive engagement around the jaw,-the curved flange it preventing displacement of the appliance from its pe sition truly axial with the members a and b, and the constrictive back portion of the clip overcoming any tendency of the appli ance to creep away from the end of the anvil to impair the accuracy of the instrument.

With reference to Fig. l, it will be seen that in attempting to measure a piece,as for instance a ring or the wall of a cylinder,the concaved side of such piece would only have bearing against the anvil member at the opposite corners thereof,the end face of such member forming the chord of an arc and so that the distance between the gaging parts of the instrument is not a true measurement of the thickness; but as will be perceived in Fig. 5, the point in the hemispherical portion g of the attachable and detachable appliance, coincident with the common axis of the anvil and the jaw I), may be brought against the concave surface to gage with preciseness the true thickness of the piece.

The device may be integrally made as to the greater portion thereof of thin spring outwardly metal at insignificant cost; tutes an extremely useful auxiliary to a calipers.

An appliance a split or partially sleeve, to embrace the edge and opposite sides of the anvil provided jaw-member of a calipers, such sleeve being provided with turned lip portions at its opposite sides, and Which also has a Wall at one endth'ereof to be in contact against the end of the anvil of the calipers and which Wall for a calipersconsisting or and it consti-V cylindrical constrictive has an extension, to project toward. the movable gaging member of the calipers, which is convergent t0 the common axis of the anvil and movable gaging member, and which clip also has an annular flange adjacent said end Wall to engage around the portion of the anvil adjacent the end.

Signed by me at Springfield, Mass, in presence of the subscribing Witness.

ROBERT A. JOHNSON.

Witness Ge R. DRISCOLL.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

- i a Washington, D. C. 

